1. Field of the Invention
The present invention relates to a press arrangement for a machine for treating a fibrous pulp sheet, e.g., paper or cardboard, in a press nip (gap; opening) extending in a run direction of the fibrous pulp sheet. The press nip may be formed between a shoe press roll and a mating roll, the shoe press roll may include a flexible press sleeve circulating around a non-rotating carrier and guided around at least one press shoe of a press unit in a press nip area. The press unit may be supported on the carrier by at least one associated force element, preferably formed by a piston/cylinder unit. Outside of the press nip area, the press sleeve may be at least substantially circular-cylindrical and concentric with a sleeve axis. A plane formed at a position of a resulting force, e.g., a plane to which the at least one associated force element is substantially symmetrical, may be arranged substantially parallel to a connecting plane including the sleeve axis and the mating roll axis, and offset positioned in the run direction.
2. Discussion of Background Information
Press arrangements similar in general to the press arrangement discussed above are known in the art, e.g., from DE-A-37 08 189. Such press arrangements are used successfully in particular in press sections of paper or cardboard machines. The fibrous pulp sheet being drained is usually guided through the press nip together with at least one felt belt. A press nip, extended in a run direction of the fibrous pulp sheet, in particular has the advantage of a greater draining capacity. The interior of a press sleeve which, outside an area of the press nip is guided in at least substantially in a circular-cylindrical fashion, can be hermetically sealed toward the exterior, which eliminates risk of contamination from lubricating materials escaping outward. In addition, pressurized air can be fed into the interior of the press sleeve, inflating the press sleeve and thereby improving the smoothness of running. If the press sleeve is guided by rotatable supporting disks mounted on the carrier, the supporting disks and the interior pressure caused by the pressurized air causes the press sleeve circulating around the carrier to slide only over the press shoe, but otherwise to circulate free of any contact.
A common problem with such press arrangements is that the fibrous pulp sheet running out of the press nip may, for a while, have a joint run with the press sleeve and a felt belt before the fibrous pulp sheet detaches itself from the felt belt. Even when the joint run is only a relatively short stretch, there is a danger of an occurrence of a reverse moistening, i.e., in which the fibrous pulp sheet reabsorbs part of the fluids that had been previously drained off. The danger of such reverse moistening is increased by inflating the press sleeve, because after inflation, the joint run stretch is lengthened.
To solve this problem, in a press arrangement discussed in, e.g., DE-37 08 189, the rotational axis of the press sleeve and the two associated supporting disks may be offset against the run direction of the press sleeve relative to the press plane running through the axes of the carrier and the mating roll in the press arrangement. The offsetting of the rotational axis of the press sleeve and the associated supporting disks relative to the press plane is provided by a rotating path of the press sleeve that is eccentric to the carrier axis. The known press arrangement in particular exhibits the disadvantage that the respective guiding elements for the press sleeve, in particular with the supporting disks provided on the press sleeve ends, must be arranged eccentrically.